My Courses

Stacking fault energy in crystals affects: A Dislocation mobility B Band gap C Nuclear radius D Electron mass Explanation Lower stacking fault energy widens partial dislocations and increases ductility. A reciprocal lattice vector G satisfies: A G·R = 0 B e^(iG·R) = 1 C G = R D G = 0 Explanation This ensures periodicity…

The coordination number of an FCC lattice is: A 6 B 8 C 12 D 4 Explanation Each atom in FCC has 12 nearest neighbors. The plane (100) in a cubic crystal has a normal along: A y-axis B x-axis C z-axis D body diagonal Explanation (100) plane is perpendicular to x-axis. Zone folding in…

Miller indices are obtained by: A Taking intercepts directly B Taking reciprocals of intercepts and clearing fractions C Multiplying intercepts by lattice constants D Dividing intercepts by 2 Explanation Miller indices are reciprocals of fractional intercepts reduced to integers. The reciprocal lattice of a BCC lattice is: A BCC B FCC C Simple cubic D…

In a simple cubic crystal, the number of atoms per unit cell is A 2 B 4 C 1 D 8 Explanation A simple cubic lattice has 8 corner atoms each sharing 1/8 → total 1 atom. Miller indices (h k l) represent planes with intercepts A h/a, k/b, l/c B a/h, b/k, c/l C…

For a photon gas, internal energy U is proportional to A T B T³ C T⁴ D 1/T Explanation Blackbody: U∝T4U \propto T^4U∝T4. Entropy of photon gas varies as A T B T² C T³ D T⁴ Explanation Entropy density ∝ T³. In BE statistics, occupation number diverges when A E = μ B E…

In microcanonical ensemble, all accessible microstates have A Different probabilities B Zero probability C Equal probabilities D Probabilities depending on temperature Explanation All microstates with same E, V, N are equally likely. Canonical ensemble describes a system in thermal contact with reservoir maintaining A Constant T B Constant μ C Constant P D Constant entropy…

In Maxwell–Boltzmann statistics, particles are treated as A Indistinguishable B Fermions only C Bosons only D Distinguishable classical particles Explanation In MB statistics, occupation numbers of energy states are A Large and allowed to be negative B Unrestricted and small compared to 1 C Restricted to 0 or 1 D Restricted to even numbers only…

Probability of an event that is certain to occur equals A 0 B 0.5 C 1 D Undefined Explanation Certain event has probability 1. Two events A and B are mutually exclusive means A P(A∩B)=P(A)P(B)P(A\cap B)=P(A)P(B)P(A∩B)=P(A)P(B) B P(A∩B)=0P(A\cap B)=0P(A∩B)=0 C P(A∣B)=P(A)P(A|B)=P(A)P(A∣B)=P(A) D P(A∪B)=0P(A\cup B)=0P(A∪B)=0 Explanation Mutually exclusive means they cannot both occur. A microstate of…

Bohr’s quantization condition for angular momentum is A L=nhL = nhL=nh B L=nh/2L = nh/2L=nh/2 C L=nℏL = n\hbarL=nℏ D L=ℏ/nL = \hbar/nL=ℏ/n Explanation Bohr postulated mvr=nℏmvr = n\hbarmvr=nℏ. Bohr model fails for multi-electron atoms because A It ignores nuclear charge B It ignores electron–electron interactions C It assumes elliptical orbits D It assumes electrons…

In the photoelectric effect, stopping potential is directly related to A Intensity of incident light B Wavelength C Maximum kinetic energy of photoelectrons D Number of photons per second Explanation eV0=KEmax⁡eV_0 = KE_{\max}eV0​=KEmax​. When the frequency of light increases above threshold frequency, the photoelectric current A Increases B Decreases C Remains constant D Drops to…